How Do A Simple Calculator In Android? How To Do It Using Buttons And Single Edit Text?
I am learning Android so I want to keep things simple. I have to add two numbers and display the result in a single editbox. To add with the second number you have store the first
Solution 1:
If your calculator has no ( / ) and you don't allow entering negative numbers then a simple algorithm to calculate a constant input of numbers and operations could work like this:
You have one variable which represents the result (that you probably want to display each step in the EditText) and one to buffer unfinished results
if the operation is * or /:
apply it to the buffer
if the operation is + or -:
add buffer to result, overwrite buffer with new input
2 * 4 + 3 + 5 * 2 * 3 - 1 + 2
initially final result = 0, buffer = 1
2-> result = 0, buffer = 2 (careful here, I interpreted the initial step as*2)* 4-> result = 0, buffer = (2*4) = 8+ 3-> result = (0+8) = 8, buffer = 3+ 5-> result = (8+3) = 11, buffer = 5* 2-> result = 11, buffer = (5*2) = 10* 3-> result = 11, buffer = (10*3) = 30- 1-> result = (11+30) = 41, buffer = -1+ 2-> result = (41-1) = 40, buffer = 2
-> finally (e.g. when pressing =) add both together: Answer = 42
Solution 2:
//Below having correct programming .//I did some changes in your code.This code was working nicely try this.//`import android.os.Bundle;import android.R.integer;
import android.R.string;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
publicclassMainActivityextendsActivity {
publicEditText display;
TextView edt;
Integer c,d,r,b;
String a="0",aa;
Button b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16;
@OverridepublicvoidonCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edt=(EditText)findViewById(R.id.editText1);
b1=(Button)findViewById(R.id.button1);
b2=(Button)findViewById(R.id.button2);
b3=(Button)findViewById(R.id.button3);
b4=(Button)findViewById(R.id.button4);
b5=(Button)findViewById(R.id.button5);
b6=(Button)findViewById(R.id.button6);
b7=(Button)findViewById(R.id.button7);
b8=(Button)findViewById(R.id.button8);
b9=(Button)findViewById(R.id.button9);
b10=(Button)findViewById(R.id.button0);
b11=(Button)findViewById(R.id.button11);
b12=(Button)findViewById(R.id.button12);
b13=(Button)findViewById(R.id.button13);
b14=(Button)findViewById(R.id.button14);
b15=(Button)findViewById(R.id.button15);
b16=(Button)findViewById(R.id.button16);
b1.setOnClickListener(newView.OnClickListener() {
publicvoidonClick(View v) {
// TODO Auto-generated method stub
a=edt.getText().toString();
a=a+"1";
edt.setText(a);
}
});
b2.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
// TODO Auto-generated method stub
a=edt.getText().toString();
a=a+"2";
edt.setText(a);
}
});
b3.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
a=edt.getText().toString();
a=a+"3";
edt.setText(a);
}
});
b4.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
a=edt.getText().toString();
a=a+"4";
edt.setText(a);
}
});
b5.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
a=edt.getText().toString();
a=a+"5";
edt.setText(a);
}
});
b6.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
// TODO Auto-generated method stub
a=edt.getText().toString();
a=a+"6";
edt.setText(a);
}
});
b7.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
a=edt.getText().toString();
a=a+"7";
edt.setText(a);
}
});
b8.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
// TODO Auto-generated method stub
a=edt.getText().toString();
a=a+"8";
edt.setText(a);
}
});
b9.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
// TODO Auto-generated method stub
a=edt.getText().toString();
a=a+"9";
edt.setText(a);
}
});
b10.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
// TODO Auto-generated method stub
a=edt.getText().toString();
a=a+"0";
edt.setText(a);
}
});
b11.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
aa=a;
b=1;
a="";
edt.setText("+");
edt.setText("");
}
});
b12.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
aa=a;
b=2;
a="";
edt.setText("-");
edt.setText("");
}
});
b13.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
aa=a;
b=3;
a="";
edt.setText("*");
edt.setText("");
}
});
b14.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
aa=a;
b=4;
a="";
edt.setText("/");
edt.setText("");
}
});
b15.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
if(b==1){
c=Integer.parseInt(aa);
d=Integer.parseInt(a);
r=c+d;
}
elseif(b==4){
c=Integer.parseInt(aa);
d=Integer.parseInt(a);
r=c/d;
}elseif(b==2){
c=Integer.parseInt(aa);
d=Integer.parseInt(a);
r=c-d;
}
elseif(b==3){
c=Integer.parseInt(aa);
d=Integer.parseInt(a);
r=c*d;
}
Toast.makeText(MainActivity.this, "Result is::"+r, 10000).show();
c=0;
b=0;
d=0;
a="";
aa="";
edt.setText("");
}
});
b16.setOnClickListener(newView.OnClickListener()
{
publicvoidonClick(View v) {
// TODO Auto-generated method stub
edt.setText("");
}
});
}`
Solution 3:
Your above code was almost correct but small logic was missed in that programming . After clicking button it will store string values into "a" its ok . After that we click on operator symbol "a" will store into "aa" variable.
example:
a="4";
aa=a;//aa="4"//After you do like this below way .
c=Integer.parseInt(aa)+Integer.parseInt(a);
//In the above line c (storing integer values) = 4+4;//a having "4" and aa="4".
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